What is your definition of a "continous contract"? Is it based on volume, or based on contract expiration date, etc? I download quotes for a bunch of different expirations into a single database table, then I run a SQL query to group they by date and contract, and then delete all contracts that aren't the one with the highest volume for that particular date.
There are numerous ways to create a continuous contract, generally they rely upon tracking volume changes from one contract to another and/or expiration date. Sometimes back months are adjusted so as to normalize relative change between contracts. Whichever way, I know of no software which allows one to specify a series of input files and produces a continuous contract.
With NinjaTrader 7 and Zen fire data, you can get continuous charts for the ES and CL for several months (at least 6).
I decided to code a utility myself this weekend; built in PHP. I am using a mix of volume and open interest to locate rollover dates. Thanks for all the suggestions.